96 lines
2.8 KiB
ReStructuredText
96 lines
2.8 KiB
ReStructuredText
.. Sequences/Views//transform_view
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transform_view
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==============
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Synopsis
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--------
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.. parsed-literal::
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template<
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typename Sequence
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, typename F
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>
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struct transform_view
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{
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// |unspecified|
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// |...|
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};
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Description
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-----------
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A view the full range of ``Sequence``\ 's transformed elements.
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Header
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------
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.. parsed-literal::
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#include <boost/mpl/transform_view.hpp>
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Model of
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--------
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* |Forward Sequence|
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Parameters
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----------
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+---------------+-------------------------------+-------------------------------+
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| Parameter | Requirement | Description |
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+===============+===============================+===============================+
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| ``Sequence`` | |Forward Sequence| | A sequence to wrap. |
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+---------------+-------------------------------+-------------------------------+
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| ``F`` | Unary |Lambda Expression| | A transformation. |
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+---------------+-------------------------------+-------------------------------+
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Expression semantics
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--------------------
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|Semantics disclaimer...| |Forward Sequence|.
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In the following table, ``v`` is an instance of ``transform_view``, ``s`` is an arbitrary
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|Forward Sequence|, and ``f`` is an unary |Lambda Expression|.
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+-----------------------------------+-----------------------------------------------------------+
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| Expression | Semantics |
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+===================================+===========================================================+
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| .. parsed-literal:: | A lazy |Forward Sequence| such that for each ``i`` in the |
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| | range |begin/end<v>| and each ``j`` in for in the range |
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| transform_view<s,f> | |begin/end<s>| ``deref<i>::type`` is identical to |
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| transform_view<s,f>::type | ``apply< f, deref<j>::type >::type``. |
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+-----------------------------------+-----------------------------------------------------------+
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| ``size<v>::type`` | The size of ``v``; |
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| | ``size<v>::value == size<s>::value``; |
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| | linear complexity; see |Forward Sequence|. |
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+-----------------------------------+-----------------------------------------------------------+
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Example
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-------
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Find the largest type in a sequence.
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.. parsed-literal::
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typedef vector<int,long,char,char[50],double> types;
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typedef max_element<
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transform_view< types, size_of<_> >
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>::type iter;
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BOOST_MPL_ASSERT_RELATION( deref<iter>::type::value, ==, 50 );
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See also
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--------
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|Sequences|, |Views|, |filter_view|, |joint_view|, |zip_view|, |iterator_range|
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